Thu, 18 Aug 2022

How is GPS different from its main rival GLONASS

RBTH
11 Jan 2022, 19:55 GMT+10

Although the two systems may seem to be competitors, they often complement each other.

GLONASS, the Russian analog of the Global Positioning System (GPS) created by the U.S., began development in the 1970s as an alternative satellite-based navigation and positioning system, but it only gained prominence in the 2000s.

Cold War space race

Soviet scientists began exploring the theoretical possibility of using satellites to launch an independent navigation system back in the 1950s, around the time when the Soviet space program successfully launched the first artificial Earth satellite - Sputnik 1 - on October 4, 1957.

This pioneering theoretical work, however, progressed slowly due to a lack of funds. Then the Cold War changed all that.

By the early 1960s, the Soviet leadership learned that the USSR's archenemy, the U.S., had been working on its satellite-based navigation system since the 1950s and that work had finally produced results. The so-called Transit system developed to track the U.S. ballistic missile submarines, entered U.S. Naval service in 1964. The Soviet Union of course had to catch up. The same year, the Soviet leadership ordered the restart of the country's research in the area of satellite-based navigation.

In 1976, the system dubbed by the Soviets as Cyclone was adopted by the military. It consisted of six spacecraft orbiting near-polar orbits at an altitude of 1,000 km.

A model of the Cyclone spacecraft.

A model of the Cyclone spacecraft.

Krassotkin

The accuracy of the new Cyclone system had to be drastically improved as the error in properly identifying an object's location could be up to 80-100 meters, which is too much by modern military standards.

24 satellites

Since then, both Soviet and later Russian scientists continued to develop the groundwork laid out by the Cyclone creators.

The project regained momentum in 2001 when the Russian government adopted the federal program called "Global Navigation System" and set a roadmap for the development of the Russian satellite-based navigation system that became known as GLONASS.

Roscosmos/Global Look Press

This Russian system consists of 24 spacecraft that move in three orbital planes that each have eight devices. In contrast, the American Global Positioning System (GPS) uses the same amount of satellites but allocates them in space differently. GPS' 24 spacecraft move in six orbital planes, four satellites in each. The difference in satellite allocation in space affects user experience.

GPS vs GLONASS

Although both systems are highly accurate, GPS slightly surpasses GLONASS both in accuracy and coverage. Used separately, the systems allow for a slight error in the positioning of the tracked object. In the case of GLONASS, the error might be one or two meters more than in the case of GPS. To its advantage, GPS also has global coverage while GLONASS might lose the signal in remote parts of the world.

Start of the carrier rocket

Start of the carrier rocket "Soyuz-2" with the navigation spacecraft "GLONASS-M" on may 27, 2019 at the Plesetsk cosmodrome.

MOD Russia/Global Look Press

Yet, GLONASS is superior to GPS when it comes to positioning objects in the North, especially in circumpolar latitudes. Since the Russian satellites do not resonate with the movement of the Earth (unlike the GPS-based satellites) they do not require auxiliary correction. In practice, it translates into better reliability of the system in places where Russia needs it the most: in the Arctic where the country's Northern Fleet operates.

Roscosmos/Global Look Press

Consequently, while GPS is generally more accurate and widespread, users in northern parts of Scandinavian countries and Russia may find GLONASS to be more convenient for them.

Since the Cold War ended the two systems are used as complementary and not as competing. Most tracking devices sold on the market (including iPhones and smartwatches) allow for simultaneous use of the GPS and GLONASS, drastically increasing the accuracy of the positioning and coverage as a result.

Click here to find out more about Sputnik 1, Earth's first artificial satellite.

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